ASTR1001 Assigment 1: Supplementary
Data Release.
More information for the science team of the
USS Drongo
More Information
 In response to popular demand, here is some more
information gleaned by the astrophysics team of the
USS Drongo.
 You may or may not find this extra information
valuable!
 You don’t need to use this additional information to
get a decent mark - but if you want an extremely
high mark, you should make what use you can of
this new information.
Communications and Scanners
Division
 The Communications and Scanners division were
excited by your report of the strange, bright
featureless moon, so they turned their equipment
on it, before it set.
 Here is what they found.
Radar
 They used the USS Drongo’s powerful main radio
communications array to beam an intense pulse of
radio emission at the “moon”.
 A reflection of this pulse was detected, 4.56
seconds after the original pulse was sent.
Spectrum
 Next, they turned their spectral scanners onto the
moon.
 This was done just before it set. At this point, the
lower half of the “moon” was bright, while the top
half was dark.
Bright Half
 Here is the spectrum of
the bright (illuminated)
half, at optical
wavelengths.
 This is a plot of energy per
unit wavelength (y-axis)
against wavelength (xaxis)
An Angstrom is 0.1
nano-metres
 No optical emission was
detected from the dark side
of the “moon”.
 However, strong emission
was detected at near infrared wavelengths, shown
here.
 Furthermore, this emission
varied with time - the green
and red lines show different
spectra taken four hours
apart.
Night Side
IR Bumps
 Clearly most of the IR emission from the dark side
comes out at particular wavelengths, forming
bumps in the spectrum.
 One of the scanners was tuned to look only at
emission at the wavelength of one of these bumps:
the one at a wavelength of 2.3 microns (micrometres).
 It was then pointed at the “moon”
Pictures of the Moon.
Here are four pictures of
the emission at this
wavelength.
1
2
3
4
They were taken at four
hour intervals, just before
it set. The order is
indicated by the numbers.
The bottom right of each
image is masked off to
avoid the scanned being
swamped by emission
from the bright side of the
“moon”.